drm/msm/dpu: Remove dynamic allocation from atomic context

drm/msm/dpu: Remove dynamic allocation from atomic context

We know the upper bound on # of mixers (ie. two), so lets just allocate
this on the stack.

Fixes:

   BUG: sleeping function called from invalid context at include/linux/sched/mm.h:201
   in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid: 0, name: swapper/0
   INFO: lockdep is turned off.
   irq event stamp: 43642
   hardirqs last  enabled at (43641): [<ffffffe24dd276bc>] cpuidle_enter_state+0x158/0x25c
   hardirqs last disabled at (43642): [<ffffffe24dfff450>] enter_el1_irq_or_nmi+0x10/0x1c
   softirqs last  enabled at (43620): [<ffffffe24d4103fc>] __do_softirq+0x1e4/0x464
   softirqs last disabled at (43615): [<ffffffe24d48bd90>] __irq_exit_rcu+0x104/0x150
   CPU: 0 PID: 0 Comm: swapper/0 Tainted: G        W         5.15.0-rc3-debug+ #105
   Hardware name: Google Lazor (rev1 - 2) with LTE (DT)
   Call trace:
    dump_backtrace+0x0/0x18c
    show_stack+0x24/0x30
    dump_stack_lvl+0xa0/0xd4
    dump_stack+0x18/0x34
    ___might_sleep+0x1e0/0x1f0
    __might_sleep+0x78/0x8c
    slab_pre_alloc_hook.constprop.0+0x48/0x6c
    __kmalloc+0xc8/0x21c
    dpu_crtc_vblank_callback+0x158/0x1f8
    dpu_encoder_vblank_callback+0x70/0xc4
    dpu_encoder_phys_vid_vblank_irq+0x50/0x12c
    dpu_core_irq+0x1bc/0x1d0
    dpu_irq+0x1c/0x28
    msm_irq+0x34/0x40
    __handle_irq_event_percpu+0x15c/0x308
    handle_irq_event_percpu+0x3c/0x90
    handle_irq_event+0x54/0x98
    handle_level_irq+0xa0/0xd0
    handle_irq_desc+0x2c/0x44
    generic_handle_domain_irq+0x28/0x34
    dpu_mdss_irq+0x90/0xe8
    handle_irq_desc+0x2c/0x44
    handle_domain_irq+0x54/0x80
    gic_handle_irq+0xd4/0x148
    call_on_irq_stack+0x2c/0x54
    do_interrupt_handler+0x4c/0x64
    el1_interrupt+0x30/0xd0
    el1h_64_irq_handler+0x18/0x24
    el1h_64_irq+0x78/0x7c
    arch_local_irq_enable+0xc/0x14
    cpuidle_enter+0x44/0x5c
    do_idle+0x248/0x268
    cpu_startup_entry+0x30/0x48
    rest_init+0x188/0x19c
    arch_call_rest_init+0x1c/0x28
    start_kernel+0x704/0x744
    __primary_switched+0xc0/0xc8

Fixes: 78d9b458cc21 ("drm/msm/dpu: Add CRC support for DPU")
Signed-off-by: Rob Clark <robdclark@chromium.org>
Link: https://lore.kernel.org/r/20211023160016.3322052-2-robdclark@gmail.com
Signed-off-by: Rob Clark <robdclark@chromium.org>